Description (adapted from the application). The Molecular Virology Core will have three distinct functions to support research on the human hepatocyte cell culture model of HCV replication and liver cell injury. The three functions of the Molecular Virology Core are: 1) to provide HCV RNA from infectious clone sources and viremic sera from infected patient sources for use in infectivity studies; 2) to characterize HCV replication in the human hepatocyte model by quantitative assessment of HCV genome and antigenome production; and 3) track propagation of HCV quasispecies variants in hepatocyte culture by heteroduplex mobility analysis and nucleotide sequencing. These functions are also components of the other sections of the application, and in this regard the Molecular Virology Core will be a service facility. In addition, several key hypotheses on HCV infectivity and viral determinants of hepatocellular injury will be explored.